1. Field of the Invention
The present invention relates to an image processing apparatus and method, and a printer and display apparatus, for use in forming and viewing a stereo image.
2. Description Related to the Prior Art
A technique for displaying a stereo image by use of a lenticular sheet is known, the lenticular sheet having a large number of rod-shaped lenticules (cylindrical lenses) arranged in a horizontal direction. Stripe images, which are formed in a stripe manner by dividing right and left viewpoint images obtained by taking from right and left viewpoints, are arranged on a back surface of the lenticular sheet in an alternate manner. Two adjacent stripe images included in the stripe images are positioned under one of the lenticules. Right and left eyes view the right and left viewpoint images with disparity through the lenticules, so that the stereo image can be viewed. Also, it is known to divide a multi-view image constituted by N viewpoint images (N is equal to or more than 3) in a stripe manner. N of the stripe images are disposed behind one of the lenticules, so that stereoscopic effect can be enhanced (for example, JP-A 2011-154301).
An image included in the stereo image (hereinafter referred to as a stereo view image or object representation) is recognized by a viewer in a representing position in a back-to-front direction according to disparity. To record the multi-view image on the lenticular sheet, a relative position relationship between the viewpoint images is set normally in a state without disparity at one point within the multi-view image, for example, at a principal object. Therefore, the stereo view image of the principal object is viewed on the lenticular sheet. A stereo view image of an object nearer than the principal object is viewed on a more forward side than the lenticular sheet. A stereo view image of an object farther than the same is viewed on a more backward side than the lenticular sheet.
Also, occurrence of crosstalk is known, because of a characteristic of the lenticules in the lenticular sheet upon viewing the multi-view image through the lenticular sheet. The crosstalk is a phenomenon in which one of the viewpoint images to be viewed property and one of the viewpoint images adjacent thereto are viewed simultaneously upon viewing from one viewpoint with one eye. Multiple overlapping images become viewed with a plurality of the viewpoint images overlapped together. A technique in relation to the crosstalk is known, in which disparity of the viewpoint images is automatically adjusted according to a stereoscopic display device for use in viewing the stereo image (See JP-A 2006-115198).
In JP-A 2006-115198 mentioned above, steps are performed serially, including a step of acquiring disparity between the viewpoint images in the stereo image, a step of acquiring device information related to a stereo display device for use in viewing, a step of determining a virtual viewpoint position corresponding to a plurality of the viewpoint images to be generated from the stereo image, and a step of generating a virtual viewpoint image according to the virtual viewpoint position being determined. The virtual viewpoint position corresponds to a photographing position of a camera for virtually photographing the virtual viewpoint image. In the course of determining the virtual viewpoint position, the disparity between the viewpoint images adjacent in the entirety of the stereo image is set equal to or less than a tolerable disparity of display while the virtual viewpoint image is displayed on the stereo display device for use. The tolerable disparity of display for use is so determined that, for example, no uncomfortable appearance is shown to a viewer even assuming that multiple overlapping images are viewed with crosstalk.
It is noted that, assuming that a relative position relationship between the viewpoint images is set without disparity, for example, at the principal object as described above, the degree of the disparity of the object increases according to greatness of the object distance with reference to the principal object between adjacent ones of the viewpoint images. Accordingly, an object with a large difference from the principal object in the object distance causes multiple overlapping images with a large offset between images due to the crosstalk, and cannot be viewed clearly. A problem may occur in decrease in the stereoscopic effect in reducing the disparity to a level equal to or less than the tolerable disparity of display as disclosed in JP-A 2006-115198.